Refrigerating apparatus



Julyz, 940- A. B. REAvls REFRIGEATING' APPARATUS 2 Sheets-Sheet l.

Filed NOV. 27, 1937 lNVENToR WITNESSES:

Patented July 2, 1940 BEFRIGERATING APPARATUS Andrew B. Reavis, Swarthmore, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 27, 1937, Serial No. 176,877

4 Claims.

My invention relates to refrigerating apparatus, more particularly to refrigerating apparatus of the vapor or steam jet type, and it has for an object to provide improved apparatus.

It is an object of my invention to improve the economy of operation of refrigerating apparatus of the vapor jet type wherein the iluid to be cooled is not directly subjected to partial evaporation but is conveyed in heat transfer relation to liquid which is cooled by partial evaporation in an evaporator.

In the patents of Kothny 1,418,002 and Schmidt 1,483,990, there is disclosed and claimed refrigerating apparatus of the stage cooling type. The liquid to be cooled is conveyed in series through a plurality of evaporator chambers, in each of which it is partially cooled by evaporation of a portion of the liquid. The chambers operate at successively lower pressures, so that greater economy of operation is effected than when the cooling to the nal temperature is eiected in a single evaporator chamber It is a particular object of my invention to provide the improved economy of operation of stage cooling in refrigerating apparatus wherein the fluid to be cooled is conveyed in heat transfer relation to liquid which is cooled by partial evaporation.

In accordance with my invention, I provide refrigerating apparatus of the vapor jet type comprising a plurality of evaporator chambers.

A group of heat transfer elements, such as a bank of tubes, is provided in each evaporator chamber and the several groups are connected in series for ow of iiuid to be cooled. Provision is made in each chamber for supplying a nlm of liquid, preferably water, n the outer surfaces of the tubes. Such provision includes apump common to the several chambers and conduit means for draining the unevaporated water from the several evaporator chambers to the pump.

The above and other objects are effected by my invention as will be apparent from the. following description and claims taken in accordance with the accompanying drawings, forming a part of this application, in which:

Fig. 1 is a side elevation, partly in section, of

- apparatus embodying my invention; and

Fig. 2 is r1 plan view thereof.

Referring to the drawings in detail, I show an evaporator or cold tank I0 having a partition Il dividing the interior thereof into chambers l2 and I3. A bank of tubes Il extends through the chamber I2, and a bank of tubes I5 extends through the chamber I3. The water or other iluid to be cooled is conveyed through the tube banks Il and I5 in series. It is delivered to the evaporator unit through a conduit I6 (see Fig. 2), flows through the lower half of the tubebank I4 in one direction and through the upper 6. half in the opposite direction. It is then conveyed through a conduit I'l to the lower half of the tube bank I5 through which it ows in one direction and then through the upper portion in the opposite direction. It is then discharged to a conduit I8, from which it is conveyed to the point of use.

A lm of water is provided on the outer surfaces-of the tubes Il and I5. Such lm of water is preferably provided by spraying water onto the tube banks, for which purpose groups of spray nozzles I9 and 20 are provided in the chambers I2 and I3, respectively. The water which is not evaporated on the surfaces of the tubes collects in the bottom of the chambers I2 and I3 and ows by gravity through connecting conduits 2l and 22 to a. well 23. From the latter, it flows ,through a conduit 23a to a. pump 24 which delivers the same under pressure through a conduit '25 to the spray nozzles I9 and 20. Make-up water, to replace the water evaporated, is admitted in any suitable manner. For example, it may be supplied through a conduit 23h to the conduit 23a'.

To remove the water vapor from the evaporator chambers, steam motivated ejectors are provided. Two ejectors 26 and 21 have their suction inlets connected to the chamber I2 and two ejectors 28 and 29 have their suction inlets connected to the chamber I3. Motive uld, such as steam under pressure, is supplied to the several jets for motivating the same through a steam main 30 and branch conections 3|. Suitable valves are provided in the connecting conduits 3| in order that the ejectors may be individually rendered operable or inoperable. Solenoid operated valves 32 and 33 are provided for the ejectors 26 and 28, respectively, while manually actuated valves 34 are provided for the ejectors 21 and 29.

A valve 3|' is provided between the suction inlet 45 of each ejector and the associated evaporator chamber to cut ol reverse ilow therethrough when the ejector is shut down. The actuation of the valve 3l' is correlated tothe actuation of the steam valves, in a manner known prior to my invention (for example, as described and claimed in Patent No. 2,129,097v of D. W. R. Morgan, dated September 6, 1938) and which need not, therefore, be considered here, it being sumcient to state that each valve 3l' is closed whenever the 65 associated ejector is not. effective to withdraw` vapor from the evaporator chamber.

The ejectors discharge into a condenser 35, which is shown as a surface condenser. The condenser 35, is preferably divided into two chambers 36 and 31, by a partition 38. The ejectors 26 and 21 discharge into the chamber 36 and the ejectors 28 and 29 discharge into the chamber 31. The chamber 36 contains a bank of tubes 39 and the chamber 31 contains a bank of condenser tubes 40. Cooling water is conveyed through these tubes to condense the vapor exhausted from the ejectors, the cooling water being circulated through the tube banks 40 and 39 in series. The cooling water may be supplied, for example, through a conduitl 4I, ow through the lower portion of the tube bank 40 in one direction and then through the upper portion in the opposite direction. A conduit 42 conveys the cooling water to the lower portion of the tube bank 39, through which it flows in one direction and then through the upper portion in the opposite direction. From the latter, it is discharged through a conduit 43.

Inasmuch as the temperature of the cooling water owing from the tube bank 40 to the tube bank 39 has been increased due to the heat that it has absorbed in the tubes 40, the vapor pressure maintained in the chamber 36 is higher than that maintained in the chamber 31. Provision is made in the condensate removal means and the air removal means for maintainingl such pressure diii'erence. The condensate collecting in the chamber 31 is drained by gravity into a conduit 44 while the condensate collecting in the chamber 36 is conveyed to the conduit 44'through a conduit 45 arranged in the form of a loop to provide a hydrostatic or liquid seal.

The air outlet 46 for the chamber 36 is connected through a conduit 41 to the chamber 31 so that the air and condensable gases collecting in the chamber 36 are vented to the chamber 31 by the pressure difference existing therein. The chamber 31 is provided with an air outlet 48 connected to any suitable air removal means.

If automatic control of the ejectors is desired, it is preferably effected in response to the temperature of the cooled water discharged in the conduit I 8. Such control includes a thermostatic bulb 49 subjected to the temperature of the water discharged from the conduit I8 and connected by a tube 58 to a bellows 5I. The latter is connected to contacts 52 and 53, which are closed successively upon increase in temperature. The contacts 52 control a solenoid 54 connected to the steam valve 33 of the ejector 28 and the contacts 53 control a solenoid 55 which actuates the steam valve 32 of the ejector 26. l

' Operation i Assume first that at least one ejector of each of the chambers I2 and I3 is in operation and is effective to reduce the pressure therein by removing vapor from the chamber. The reduced pressure lowers the boiling point of the water sprayed onto the tubes therein, and a portion of the water is vapcrized by the heat extracted from the water owing through the tubes.

Since more water is sprayed onto the tubes than is immediately evaporated, the excess drains from the chambers I2 and I3 to the well 23 and is recirculated by the pump 24 to the spray v nozzles I9 and 29.

The water owing through the tubes I4 and I5 is thus cooled in stages, so that the temperature of the water flowing through th'e tubes I4 is lower than the temperature of the water iiowing `ment provides a more nearly uniform compression ratio for the two groups of ejectors.

l The above described apparatus provides operation at high economy due to the higher evaporator pressure` maintained in the chamber I2, which enables the ejectors connected thereto to provide removal of a greater quantity of vapor for a given quantity of steam than if the chamber I2 oper- Because of this diiference ated at the same pressure as the chamber I3. If 4 the tubes I4 and I5 were disposed in a common chamber, such chamber would necessarily operate at the lowest evaporator pressure in order to cool the water owing through the tubes down to the desired low temperature.

It will be noted that the connecting conduits 2| and 22 are arranged to provide a hydrostatic seal between the chambers I2 and I3, in order to permit different pressures to be maintained therein. The difference in pressures effects some diierence in liquid level therein, but the difference in liquid level is very small.

When the cooling load is suiciently low, only one ejector may be operated. In such case, water is cooled in the tubes of only one evaporator chamber and flows through the tubes of the other evaporator chamber without being cooled.

Referring to the control of the ejectors, operation of onefor both of the ejectors 21 and 29 may be effected by means of the manually controlled valves 34 to provide for the base or minimum load. 'I'he variations in load are taken by the automatic ejectors 26 and 28. Upon increase in temperature of the water being cooled, the bellows 5I expands and first closes the contacts 52 to effect operation of the ejector 28 and then closes the contacts 53 to start the ejector 26. Upon decrease in temperature, the ejector 26 is rlrst shut down and then the ejector 2l.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited but is susceptible .of various changes and modifications without departing from the spirit thereof, and I desire, therefore, thaty only such limitations shall be placed there- -upon as are imposed by the prior art or as are specically set forth in the appended claims.

What I claim is:A

1. In refrigerating apparatus, the combination of a plurality of evaporator chambers; conduit means in each chamber; a uid translating element associated with each chamber for withdrawing vapor therefrom to effect cooling by partial evaporation of liquid; means for wetting the exterior surfaces of said conduit means including a pump common to said chambers, means the several chambers in series, whereby said iiuid is cooled in stages and said chambers operate at successively lower pressures.

2. In refrigerating apparatus, the combination of a plurality of evaporator chambers; conduit means in each chamber; an ejectorl associated with each chamber for withdrawing vapor therefrom to eifect cooling by partial evaporation of liquid; means for wetting the exterior surfaces of said conduit means including a pump common to said chambers, means for conveying unevaporated liquid from said chambers to said pump and arranged to form a liquid seal between said chambers, and means for conveying liquid from said pump to the exterior surfaces of said conduit means in the respective chambers in parallel; and means for conveying iiuid to be cooled through the conduit means in the several chambers in series, whereby said iiuid is cooled in stages and said chambers operate at successively lower pressures.

3. In refrigerating apparatus, the combination of iirst and second evaporator chambers; conduit means in each chamber; first and second iiuid translating elements connected to said rst and second chambers, respectively, for withdrawing vapor therefrom to eifect cooling by partial evaporation of liquid; means for supplying liquid to the outer surfaces of the conduit means in the several chambers including a pump common tov said chambers. means for conveying unevaporated liquid from said chambers to said pump and arrangedtoformaliquidsealbetweensaidcham ond condensing chambers connected to said iirst and second translating elements, respectively, for receiving the fluid exhausted therefrom; and means for conveying cooling uid in heat transfer relation to said second and first condensing chambers in series in the order naned, whereby said second condenser chamber operates at lower pressure than said first condenser chamber.

4. In refrigerating apparatus, the combination of a plurality of evaporator chambers sealed from each other, conduit means in each chamber, an ejector connected to each chamber for withdrawing vapor therefrom to effect cooling by partial evaporation of liquid, means for supplying liquid to the outer surfaces of the conduit means in the several chambers; the conduit means in one of the evaporator chambersv being connected in series with the conduit means in another of the evaporator chambers, whereby said liquid is cooled in stages and said chambers operate at successively lower pressures, and means for automatically controlling one of said electors in response to demand for cooling of liquid ilowing through said conduit means.

ANDREW B. REAVIS. 

